a new tree:
reproduction and cloning
How are new sugar maple
trees created for mature ones?
Here we discuss two ways: seed reproduction and cloning.
you may have learned that under normal conditions, trees reproduce
naturally through seed reproduction. Here we discuss it only briefly,
as an introduction to cloning.
naturally produced from seeds, which are created from mature trees.
Most sugar maple trees need 30 years of healthy growing before they
reach maturity. In
sugar maples and many other trees, pollen from the male reproductive
organs of a "father" tree fertilize the ovule, or female
reproductive organ, of the "mother" tree.
results in the creation of a seed (click
here to see a sugar maple seed) that eventually drops from the
tree and lands on the ground - generally nearby, but often at quite
a distance (think about how sugar maple seeds you may have seen can
travel on the wind). If the environmental conditions are right, the
seed will sprout roots, grow a shoot, and eventually become a small
seedling. The seedling will have a genetic makeup that reflects both
Do you remember
"Dolly," the cloned sheep? Foresters have been cloning trees
for years. This allows them to produce trees that are genetically
identical to the parent tree, which is particularly useful in the
Sugar Maple Tree
Improvement Program. But how do you get clones of trees?
step in cloning a tree is taking a "cutting" or branch of
the parent tree. The cuttings can then be "grafted" or allowed
to grow onto roots ("root stock") of an existing tree. If
you are familiar with grafting apple trees, you know that any genetic
characteristics of the apple tree cutting will be expressed above
the point where the cutting is grafted onto the rootstock. For example,
if you take a cutting from an apple tree with crisp, green apples,
and graft it onto rootstock from a tree with mushy, red apples, the
new tree will produce crisp, green apples above the point where it
is grafted. This same principle would hold for maple trees. If sap
sweetness is genetically controlled, then a grafted tree should have
similar sap sweetness to the parent cutting above the point where
the tree is grafted.
cuttings can be "rooted." This involves treating the cuttings
with hormones under special greenhouse conditions so that the cuttings
form their own roots. It can be a tricky business as it involves growing
the cuttings under just the right temperature, moisture, light, and
nutrient conditions. Scientists from the U.S. Forest Service and Cornell
University have pioneered new methods of developing roots on sugar